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re: plans to make pool solar heater
11 apr 1998
mark main wrote:
>bourque@microtec.net wrote in message
>>i am looking for a plan to make my own solar system to heet my pool...
pool heeting is easy. keeping the heet in isn't, unless you...
>1. cover your pool at night to retain the heat of the day.
you might make a foamboard + concrete cover that automatically floats at
night (with some air pumped into pvc pipes) and sinks during the day
(water in pipes), with a "solar pool cover" over that, to reduce heat
loss by evaporation, and surround the pool with asphalt or a 20' skirt
of pebbles over black plastic to keep rainwater from washing the heat
out of the surrounding soil, ie to effectively insulate the sidewalls
and add thermal mass.
where i live, in december, a 70 f 24x36x8' deep pool with us r20 sides
and bottom would lose about 24h(70f-54f)1824ft^2/r20 = 35k btu/day to
the soil, and another 18h(70f-23f)24'x36'/rc = 731k/rc btu/day through
a us rc cover at night, and 6h(70f-38f)24x36/r1 = 166k btu/day through
the "solar pool cover" during the day, and gain about 620x0.9x24x36
= 482k btu/day of solar heat through the cover, so if the solar energy
that flows into the pool equals the heat energy that flows out during
an average december day, 482k = 35k + 731k/rc + 166k, so rc = 2.6.
an inch of beadboard (r4) or styrofoam (r5) insulation might be enough,
or more, if the cover is in 4x8' modular rafts tied together with
uninsulated gaps between them.
nick
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